1. Field of the Invention
The disclosure relates to a liquid crystal display, and more particularly, to a liquid crystal display having common-voltage compensation mechanism and related common-voltage compensation method.
2. Description of the Prior Art
Liquid crystal displays (LCDs) have advantages of a thin profile, low power consumption, and low radiation, and are broadly adopted for panel displaying in a variety of electronic products. The operation of a liquid crystal display is featured by modulating the voltage drop across opposite sides of a liquid crystal layer for twisting the angles of liquid crystal molecules in the liquid crystal layer so that the transmittance of the liquid crystal layer can be controlled for illustrating images with the aid of light source provided by a backlight module. It is well known that the polarity of the voltage drop across opposite sides of the liquid crystal layer should be inverted periodically for protecting the liquid crystal layer from causing permanent deterioration due to polarization, and also for avoiding an occurrence of image sticking phenomenon on the LCD screen. Accordingly, various inversion operations, such as frame-inversion driving operations, line-inversion driving operations, pixel-inversion driving operations and dot-inversion driving operations, are developed to drive the liquid crystal display for improving image display performance.
FIG. 1 is a circuit diagram schematically showing a prior-art liquid crystal display 100. As shown in FIG. 1, the liquid crystal display 100 comprises a plurality of data lines 110, a plurality of gate lines 120, a plurality of pixel units 130 and a common voltage generator 190. The data lines 110 include a data line DLi for transmitting a data signal SDi, the gate lines 120 include a gate line GLj for transmitting a gate signal SGj, and the pixel units 130 include a pixel unit Pij having a data switch 135, a liquid-crystal capacitor Clc and a storage capacitor Cst. The data switch 135 is utilized for providing a control of writing the data signal SDi according to the gate signal SGj, thereby generating a desired pixel voltage Vij. The common voltage generator 190 is employed to provide a common voltage Vcom furnished to a common electrode COM. Since parasitic capacitor Cd exists between the data line DLi and the common electrode COM, and since parasitic capacitor Cg exists between the gate line GLj and the common electrode COM, both the voltage changes of the data signal SDi and the gate signal SGj have an effect on the common voltage Vcom at the common electrode COM, which is known as the phenomenon of crosstalk interference occurring to the operation of the liquid crystal display 100. In particular, if adjacent pixel data of a frame to be displayed include lots of black/white gray-level switching pixel data, the aforementioned inversion driving operation of the liquid crystal display 100 is likely to cause serious crosstalk interference, which leads to an occurrence of significant pixel brightness distortion and degrades the display quality on the LCD screen.